A fast fault current calculation method for distribution networks connected with inverter interfaced distributed generators

Integration of distributed generators (DGs) into a distribution network (DN) can impact on the reliability operation and stability of protection systems. Depending on DG types, their installed locations, and operation states, fault current values in the distribution network can be significantly changed such that protective devices can inaccurately operate. Traditional fault analysis methods have not considered the presence of distributed generators and their operation characteristics, bidirectional power flows and change in bus-voltage values in the DN. Therefore, improvement of fault current calculation methods is necessary to fast, automatically and accurately determine fault current values in the DN with distributed generators. Hence, this paper develops an improved fault analysis method based on bus-voltage thresholds determination for distribution networks with DGs. The bus-voltage thresholds can be evaluated by determining load power confidence intervals (LPCI), and fault current thresholds will be then calculated in the DN with DGs. Based on a developed LPCI calculation tool and E-terra distribution software, achieved simulation results have validated the effectiveness of fault analysis method based on bus-voltage thresholds for distribution networks in case of considering types, locations and operation states of various distributed generators.

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An improved fault current calculation method and protection scheme of Doubly-fed Induction Generator

Energy Reports ◽

10.1016/j.egyr.2021.08.107 ◽

2021 ◽

Vol 7 ◽

pp. 5168-5174

Author(s):

Jun Yin

Keyword(s):

Calculation Method ◽

Induction Generator ◽

Fault Current ◽

Doubly Fed Induction Generator ◽

Protection Scheme ◽

Doubly Fed ◽

Current Calculation

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An asymmetrical fault current calculation method of synchronverter

2019 IEEE Applied Power Electronics Conference and Exposition (APEC) ◽

10.1109/apec.2019.8721858 ◽

2019 ◽

Author(s):

Lili He ◽

Wen Huang ◽

Zhikang Shuai ◽

Z. John Shen

Keyword(s):

Calculation Method ◽

Fault Current ◽

Current Calculation

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Simplified and Automated Fault-Current Calculation for Fault Protection System of Grid-Connected Low-Voltage AC Microgrids

International Journal of Emerging Electric Power Systems ◽

10.1515/ijeeps-2017-0011 ◽

2017 ◽

Vol 18 (2) ◽

Cited By ~ 3

Author(s):

Duong Minh Bui

Keyword(s):

Low Voltage ◽

Operation Mode ◽

Distribution Coefficients ◽

Fault Analysis ◽

Fault Current ◽

Analysis Method ◽

Distributed Generators ◽

Overcurrent Relays ◽

Current Calculation ◽

Ac Microgrid

Abstract Fault currents inside a grid-connected AC microgrid are significantly varied because fault current contributions of the main grid and DG units are different from each other due to various fault locations, fault types, and high penetration of inverter-based distributed generators (IBDGs) and rotating-based distributed generators (RBDGs). A traditional fault-analysis method cannot be sufficiently applicable for AC microgrids with the presence of both rotating-based distributed generators and inverter-based distributed generators. From the above viewpoint, this paper proposes a simplified and automated fault-current calculation approach for grid-connected AC microgrids to quickly and accurately calculate fault-current contributions from IBDGs and RBDGs as well as the grid fault-current contribution to any faulted microgrid sections. The simplified and automated fault-current calculation approach is mainly focused on grid-connected and small-sized low-voltage AC microgrids with the support of communication system. Under the grid-connected microgrid operation mode, fault-tripping current-thresholds of adaptive overcurrent relays are properly adjusted thanks to the proposed fault analysis method. Relying on fault-current distribution-coefficients of IBDGs, RBDGs, and the utility grid, the setting values of adaptive overcurrent relays in a low-voltage AC microgrid are effectively self-adjusted according to various microgrid configurations and the operation status of DG units during the grid-connected mode.

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